Packaging of integrated circuit devices is becoming increasingly more difficult and complex in view of the increased number of input/output connections being required for the carrier-mounted chip devices. Multiple hundreds of connections are not uncommon with the accompanying number of leads. One way external connections are provided is to mount a chip on a substrate carrier whereby the contact pads on the chip are aligned with contacts appropriately arranged and typically in a matrix pattern on one side of the carrier. These contacts on the one side of the carrier communicate via conductive traces within the carrier to contacts on the other side of the carrier to which are connected the leads of the leadframe. Alternatively, as permitted by some device designs, the contact pads to be connected to the leadframe could be located on the same side of the carrier to which the chip is mounted. Thus, in the resultant packaged chip device, external leads are electrically connected as required to the chip.
A present process used for attaching a leadframe to a carrier includes the combination of the use of a brazing fixture and visual alignment of the leads of the leadframe and the pads on the carrier. The fixture consists of two parts and both are usually made of a graphite material but could also be made of other materials including ceramic materials. The first part holds a ceramic substrate or carrier and the second part is placed over the first part and holds the leadframe. This arrangement, however, is only able to grossly or coarsely position the leads of the leadframe with respect to the pads on the carrier. This is so because of the differences in coefficients of thermal expansion, amongst the fixtures, the carrier and the leadframe. It has been experienced that there has to be a considerable amount of spatial play built into the various elements amongst the respective fixtures, the carrier and the leadframe in order to accommodate for these thermal mismatches. No way is presently known that fixtures can be built to result in precise alignment of the leads on the leadframe and the pads on the carrier because a considerable amount of play amongst the elements is required when connections are accomplished using silver brazing which requires temperatures of 800.degree. C. to 1000.degree. C. or even at lower temperatures for solder brazing. To accomplish the solder reflow of the pads, the combination of the assembled elements is placed in a furnace. Thus, significant play is required to accommodate the need for the differences in thermal expansion. With the presently known apparatus and process involved, only gross positioning of the various elements is possible and fine positioning results from a visual alignment of the leads and the pads by a human operator. The leads are then bonded to the pads.